It is difficult to appropriately size the trailing edge orifices of an internally cooled airfoil in order to efficiently meter the flow of cooling air leaving the airfoil. The difficulty of metering the air principally arises because of manufacturing constraints. For example, internally cooled airfoils are typically cast using a ceramic core, and a minimum core thickness (about 0.020 inch) must usually be maintained to prevent core breakage upon removal. It is therefore difficult to provide an airfoil requiring a less than 0.020 inch orifice size. An oversize orifice, however, result in wasted cooling air efficiency.
Accordingly, there is a need to provide a new airfoil cooling flow metering device which addresses these and other limitations of the prior art.